Mercury cathode electrolysis apparatus



Aug. 1l, 1953 A. BAslLr-:wsKY

MERCURY CATHODE ELEcTRoLYsIs APPARATUS Filed March 19, 1951 WullnINVENTOR. 144 'X/s 9A su. fwd/ry Patented Aug. 1l, 1953 MERCURY CATHODEELECTROLYSIS APPARATUS Alexis Basilewsky, Sea Cliff, N. Y., assignor toSolvay & Cie, Brussels, Belgium, a Belgian com- Dany Application March19, 1951, Serial No. 216,441

6 Claims. (Cl. 204-21-9) This invention relates to electrolysisapparatus wherein a chemical compound is decomposed by electricalcurrent to produce a gas as at least one of the products of thedecomposition, and is more particularly concerned with electrolyticapparatus of the mercury cathode type comprising elongated substantiallyhorizontal cells.

Mercury cathode cells of the type used commercially for example todecompose sodium chloride in aqueous solution to produce chlorine andsodium, comprise relatively narrow elongated troughs slightly inclinedto permit the longitudinal gravity flow of mercury over the bottomthereof and are provided With depending graphite anodes having a lowerface spaced at a predetermined distance from the Surface of the iiowingmercury cathode. In operation, the liberated sodium or other metal formsan amalgam with the mercury which ows out of the cell by gravity. Thechlorine or other gas liberated in the reaction is removed by suitablemeans.

Cells of this type have one or more covers which support the graphiteanodes and rest upon the side and end walls of the trough. To clean theapparatus, a procedure which is required from time to time in order toinsure ef- Iicient operation, it is necessary to remove the cover. Sincethe apparatus operates under a slight vacuum, when the cover is removedthere is an appreciable in-rush of air. This incoming air not onlygreatly dilutes the chlorine or other gas formed in the cell butcontaminates the gas to an extent which renders it unsuitable for manypurposes and thus necessitating a difficult separation.

It has, therefore, been considered necessary in practice to shut downthe cell completely When any prolonged opening of the apparatus isnecessary, e. g. for cleaning or inspection. It has not been heretoforethought possible to clean or make a complete inspection of anelectrolytic cell while it is in operation. The cleaning and inspectionof cells has, therefore, resulted in appreciable lost production. Thecell must be completely shut down duringthe entire cleaning orinspecting operation.

The principal object of the invention is to provide means for permittingthe inspection and cleaning of an electrolytic cell Withoutnecessitating the shutting down of the cell and without causingcontamination by air of the gas evolved in the cell.

In accordance with the invention, I provide an electrolytic cell of atype having a gas outlet at each end thereof, and preferably a thirdoutlet, and having a plurality of transverse partitions dividing thecell into a series of compartments. The partitions extend from the topof the cell downwardly below the surface of the electrolyte butterminate short of the bottom or sole of the cell so'that flow ofelectrolyte and mercury is not impeded. The cell is provided withelectrolyte outlet means which determine the level of the electrolyteand the partitions are of sufficient height to extend into theelectrolyte a suiiicient distance to form a gas seal but to permit freeow of amalgam and electrolyte. In the upper portion of each partitionthere is provided at least one opening, preferably of circularcross-section. These openings are sufciently high that they will bepositioned above the level of the electrolyte when the cell is in normaloperation. Cooperating with these openings or apertures are Stoppersadapted to fit into the apertures and to form a fluid-tight closuretherefor.

The cover for the cell is formed from a plurality of cover plates orslabs which are dimensioned to rest upon the side Walls of the cell andadvantageously are formed to rest upon the partitions as well. An anodeis supported by each cover slab and extends downwardly into therespective cell compartment. It is a feature of the invention that eachcover plate or slab iS adapted to be removed independently of the otherslabs, and when a cover is removed the Stoppers are readily insertablein the apertures of the thus-opened cell compartment to prevent flow ofair into the adjacent compartments and thereby to permit cleaning of theopened compartment without interrupting the operation of the cell.

Other objects and features of the invention will be apparent from thefollowing detailed description thereof and from the drawings wherein,

Fig. 1 shows in cross-section, a mercury cathode electrolytic cellembodying features of the invention;

Fig. 2 is a similar View of another embodiment of the cell;

Fig. 3 is a sectional view taken approximately along the line 3 3 inFig. 1. l

Referring to the drawing, the numeral l0 designates an elongatedelectrolysis trough which is supported by members I 2 and is adapted tocontain the electrolyte I4, e. g., aqueous sodium chloride solution, andthe owing mercury cathode I6. An inlet I8 for the mercury is shown atone end of trough I0 and an outlet I9 for the amalgam formed by themercury and the metal liberated during the electrolysis at the oppositeend of the trough. The electrolyte inlet is shown at 22 and theelectrolyte outlet is shown at 24, the outlet 24 serving to determinethe level of the electrolyte in the cell and may be convenientlyprovided with: a trap or like means to insure the. maintenance of thedesired level. Extending between the side walls of trough l are lateralpartitions 30 which divide the. upper portion of the trough l0 into aseries of adjoining and communicating compartmentsA 32. It will beobserved that the partitions extend downwardly below the surface-of theelectrolyte I4 but do not extendto thesurfaceof theV flowing mercurycathode I6, thereby permitting free flow of the cathode and the.electrolyte i4 under the partitions. 'Ihe partitions are convenientlyremovably received in recesses 34a formed in the side walls of trough l0as shown in. Fig. 3 in substantially gas-tight engagement, or thepartitions 30, may be formed integrally with the walls of trough HJ, asby welding. Preferably, as shown, the lower edge 33 of partitions 30 isabove the surface of the horizontal anodes 34 and are below theelectrolyte level a sufcient distance to form a gas seal to prevent owof gas under the partitions. The spacing of the lower edge 33 of thepartitions 30 with respect to the bottom of the cell may vary, but

generally speaking the partitions 30 will extend downwardly for 2/3 to1%, of the trough height. As shown in the embodiments of Figs. l and 2,resting upon the upper edge of each pair of partitions 30 is a coverslab in which is supported f the anode 33 which extends through thecover slab and is sealed thereto as by luting 35 or other like sealingand insulating composition. Suitable luting or packing material alsoseals the space between adjoining cover plates and between the coverplates and the side walls of trough I0. As shown in Fig. 1, the endcompartments of the cell beyond the anode compartments are provided withcover slabs 36 and the cover slabs for the intermediate anodecompartments are indicated by the reference numeral 31.

Gas outlets 38 for the ends of the cell are provided in the cover slabs36. Gas outlets 38 may conveniently be connected, as by a separablehanged-joint, to a common header (not shown) for carrying the evolvedgas to storage receptacles. Alternatively, the gas outlets may beprovided in the upper portions of the side walls of the trough I0.

Each of the partitions 30 is provided with at least one apertureY 39-positioned in the upper. portion of the partition above the level of theelectrolyte but preferably substantially below the top of the partition.The gas evolved during the operation of the cell flows through theseapertures 39 from compartment to compartment until one of the gasoutlets 38 is reached.

When it is desired to inspect or clean the cell, the cover slab of oneof the compartments is removed, the anode supported thereby havingpreviously been disconnected from thel power source. When the cover slabhas been removed, stoppers 40 are inserted in the apertures 33 of thepartitions 3B forming the end walls of the opened compartment. TheStoppers are, of.

course, formed to fit the apertures and are made from a chemicallyresistant material such as ebonite. With the compartment thus openedandsealed from the adjoining compartments,l it may be readily cleaned orinspected. Operation of the cell as a whole, however, continues withoutinterruption. The gases evolved at one side of the opened compartmentare removed through one of the outlets 38 while the gases formed on theother side of the opened compartment are removed through the otheroutlet 38. The aperturesr 33 in the partition wallsY permit theuninterrupted ow of gas fromA compartment to compartment until one ofthe two gas outlets is reached. Since the compartment partitions 30 donot extend to the bottom of the cell, ow of electrolyte and mercurycathode continues during the cleaning operation. Thus, the only loss inproductionv is that of the particular compartmentiwhich is opened. Afterthe compartment has been cleanedL the cover slab is replaced, the anodeconnected to the circuit, and the compartment is thus again placed inoperation. This procedure is repeated in each of the remainingcompartments until the entire cell has been cleaned or inspected,without, however, being completely shut down or out of operation at anytime.

While in the embodiment illustrated in Fig. 1 I have shown a cell havinga gas outlet at each end of the cell and positioned in each of the endanode compartments, I advantageously also provide a third gas outlet.Referring to Fig. 2, there is shown a mercury cathode electrolytic cellsimilar to that of Fig. 1 but having end gas outlets 38a. in the upperportion of the cell side wall and a. third gas outlet 45 in the sidewall of the center anode compartment. This center outlet is of Valueduring normal operation of the cell whereas the end outlets are ofprimary value during cleaning and inspecting when the individualcompartments are opened. Thus, the end gas outlets 38 may be connectedto one chlorine receiver while the center outlet 45 may be connected toanother. During the cleaning of the cell by successive removal of thecover plates, as previously described, the chlorine is slightly dilutedbut in a usable commercial concentration and is removed to the receiverto which the end outlets 38a are collected. When, however, during normaloperation of the cell substantially pure chlorine is removed, this gasmay be removed through central outlet i5 and separately collected.Obviously, the outlets 38a and 45 are provided with valve means and itwill be apparent that the third outlet 45 does not have to be at theexact center of the cell. It will also be apparent that the gas outlets38a. and 45 may be provided in the cover plates as in Fig. 1 rather thaninthe side walls, although the construction shown in Fig. 3 ispreferred.

It will be understood that a uid-tight seal between the variousseparable part-s of the cell is provided in known manner by luting,gaskets or other convenient means, as indicated at 50 in the drawing,and may be held in place by bars or other convenient clamp means, asindicated at 5I.

While I have shown and described preferred embodiments of my inventionand I have pointed out certain possible modiications, it will beapparent to those skilled in the art that various other changes andmodications may be made without departing from the scope of theinvention as dened in the appended claims and it is intended, therefore,that all matter contained 1n the foregoing description and in thedrawings Shall be interpreted as illustrative and not in a limitingsense.

This application is a continuation-impart of amasser my copendingapplication, Serial filed July 17, 1947, now abandoned.

What I claim and desire to secure by Letters Patent is:

l. In an electrolysis apparatus of the mercury cathode type, thecombination of an elongated substantially horizontal cell adapted tocontain a flowing mercury cathode and a flowing aqueous electrolyte,means for maintaining the electrolyte at a fixed predetermined level,transverse partitions dividing said cell into a succession of chambers,said partitions extending from the top of said cell to below the levelof the electrolyte but terminating a substantial distance from thebottom of the cell, whereby to permit unimpeded ow of mercury andelectrolyte, each of said partitions being provided with at least oneaperture in the upper portion of but substantially below the top of thepartition, each of said apertures being adapted to receive and be closedby a stopper, and individual covers for each of said chambers removablypositioned on said cell in iluid-tight relationship with the top of thecell walls and the tops of the adjacent partitions, and gas outlets atopposite ends of the cell for removing evolved gases from said cell.

2. In an electrolysis apparatus or" the mercury cathode type, thecombination of an elongated substantially horizontal cell adapted tocontain a flowing mercury cathode and a flowing aqueous electrolyte,means for maintaining the electrolyte at a xed predetermined level,transverse partitions dividing said cell into a succession of chambers,said partitions extending from the top oi' said cell to below the levelof the electrolyte but terminating a substantial distance from thebottom of the cell, whereby to permit unimpeded flow o1" mercury andelectrolyte, each of said partitions being provided with at least onecircular aperture in the upper portion of but substantially below thetop of the partition, each of said apertures being adapted to receiveand be closed by a stopper, and individual covers for each of saidchambers removably positioned on said cell in duid-tight relationshipwith the top of the cell walls and the tops of the adjacent partitions,said covers supporting the anodes, and gas outlets at opposite ends ofthe cell for removing evolved gases from said cell.

3. In an electrolysis apparatus of the mercury cathode type, thecombination of an elongated substantially horizontal cell adapted tocontain a flowing mercury cathode and a flowing aqueous electrolyte,means for maintaining the electrolyte at a ixed predetermined level,transverse rectangular partitions dividing said cell into a successionof chambers, said partitions extending from the top of said cell tobelow the level of the electrolyte but terminating a substantialdistance from the bottom of the cell, whereby to permit unimpeded iiowof mercury and electrolyte, each of said partitions being provided witha plurality of apertures in the upper portion of but substantially belowthe top of the partition, each of said apertures being adapted toreceive and be closed by a stopper, and individual covers for each ofsaid chambers removably positioned on said cell in duid-tightrelationship with the top of the cell walls and the tops of the adjacentpartitions, and gas outlets at opposite ends of the cell for removingevolved gases from said cell.

4. In an electrolysis apparatus of the mercury cathodetype adapted tocontain a flowing mercury cathode and a flowing electrolyte, the coni-jbination of an elongated substantially horizcntal cell having gasoutlets at each end thereof and horizontal graphite anodes dependingtherein, means for maintaining the electrolyte at a xed predeterminedlevel, transverse partitions dividing said cell into a succession ofchambers, removable individual covers for each of said chambers, saidpartitions extending from the top of said cell to below the level of theelectrolyte but terminating a substantial distance from the bottom ofsaid cell and havin apertures in the upper portions of but substantiallybelow the tops of the partitions, each of said apertures being adaptedto receive and be closed by a stopper, whereby to permit cleaning of oneof said chambers without interrupting the electrolysis process in theadjacent chambers.

5. In an electrolysis apparatus of the mercury cathode type adapted tocontain a ilowing mercury cathode and a flowing electrolyte, thecombination of an elongated substantially horizontal cell having gasoutlets at each end thereof and horizontal graphite anodes dependingtherein, means for maintaining the electrolyte at a fixed predeterminedlevel; transverse partitions dividing said cell into a succession ofchambers, removable slabs serving as covers for said chambers, saidslabs cooperating with both sides of said cell and the top of saidpartitions to form fluid-tight seals, and gas outlets at opposite endsof said cell, said partitions extending from the top of said cell tobelow the level of the electrolyte but terminating a substantialdistance from the bottom of said cell and having apertures in the upperportions thereof, each of said apertures being adapted to receive and beclosed by a stopper, whereby to permit cleaning of one of said chamberswithout interrupting the electrolysis process in the adjacent chambers.

6. In an electrolysis apparatus of the mercury cathode type adapted tocontain a flowing mercury cathode and a flowing electrolyte, thecombination of elongated substantially horizontal cell having graphiteanodes depending therein, a gas outlet at each end and at approximatelythe center of said cell, means for maintaining the electrolyte at a nxedpredetermined level, transverse partitions dividing the cell into asuccession of chambers, removable individual covers for each of saidchambers, said partitions extending from the top of said cell to belowthe level of the electrolyte but terminating a substantial distance fromthe bottom of the cell and having apertures in the upper portionsthereof, each of said apertures being adapted to receive and be closedby a stopper, whereby to permit cleaning of one of said chambers withoutinterrupting the electrolysis process in the adjacent chambers.

ALEXIS BASILEWSKY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,405,129 I-Iarris Jan. 31, 1927 2,232,128 Muller Feb. 18,1941 FOREIGN PATENTS Number Country Date 22,406 Great Britain Dec. 8,1900

1. IN AN ELECTROLYSIS APPARATUS OF THE MERCURY CATHODE TYPE, THECOMBINATION OF AN ELONGATED SUBSTANTIALLY HORIZONTAL CELL ADAPTED TOCONTAIN A FLOWING MERCURY CATHODE AND A FLOWING AQUEOUS ELECTROLYTE,MEANS FOR MAINTAINING THE ELECTROLYTE AT A FIXED PREDETERMINED LEVEL,TRANSVERSE PARTITIONS DIVIDING SAID CELL INTO A SUCCESSION OF CHAMBERS,SAID PARTITIONS EXTENDING FROM THE TOP OF SAID CELL TO BELOW THE LEVELOF THE ELECTROLYTE BUT TERMINATING A SUBSTANTIAL DISTANCE FROM THEBOTTOM OF THE CELL, WHEREBY TO PERMIT UNIMPEDED FLOW OF MERCURY ANDELECTROLYTE, EACH OF SAID PARTITIONS BEING PROVIDED WITH AT LEAST ONEAPERTURE IN THE UPPER PORTION OF BUT SUBSTANTIALLY BELOW THE TOP OF THEPARTITION, EACH OF SAID APERTURES BEING ADAPTED TO RECEIVE AND BE CLOSEDBY A STOPPER, AND INDIVIDUAL COVERS FOR EACH OF SAID CHAMBERS REMOVABLYPOSITIONED ON SAID CELL IN FLUID-TIGHT RELATIONSHIP WITH THE TOP OF THECELL WALLS AND THE TOPS OF THE ADJACENT PARTITIONS, AND GAS OUTLETS ATOPPOSITE ENDS OF THE CELL FOR REMOVING EVOLVED GASES FROM SAID CELL.